Measuring strain on display device

ABSTRACT

A display includes a thin-film transistor (TFT) glass layer having a top surface and a bottom surface and a color-filter glass layer having a top and a bottom surface. The TFT glass layer extends beyond the color-filter glass layer to form an overhanging portion of the TFT glass layer. The overhanging portion is flexible, and a flexible printed circuit (FPC) is affixed to the overhanging portion. The FPC includes an integrated strain gauge for measuring strain at a plurality of locations on the overhanging portion of the TFT glass layer. The display device may be incorporated into a chassis to secure the display in the device. A processor, within the housing, may instruct the strain gauge to measure the strain.

BACKGROUND

Consumers often prefer that mobile devices, such as tablet computers,mobile telephones, and laptops, are thin and light. To achieve thin andlight devices, manufacturers may choose to reduce the weight andthickness of the housing and chassis that hold and protect thecomponents within the devices. Lighter and thinner housings and chassis,however, may make the components of the mobile device more prone tofailure. For example, dropping the device may break the display of thedevice.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates an exemplary display device in one embodiment;

FIGS. 1B and 1C illustrate an exemplary color-glass filter and anexemplary thin-film-transistor (TFT) glass layer;

FIGS. 2A and 23 illustrate exemplary cross-sectional views of displaydevices;

FIGS. 3A, 3B, 3C, 3D, and 3E illustrate exemplary strain gauges relativeto a color-glass filter and a TFT glass layer;

FIGS. 4A and 4B illustrate exemplary cross-sectional views of displaydevices with strain gauges;

FIG. 5 illustrates an exemplary strain-gauge in one embodiment;

FIG. 6 is a block diagram of exemplary components in one embodiment of adisplay device;

FIG. 7 is a block diagram of an exemplary environment for implementingembodiments described herein;

FIG. 8A is a block diagram illustrating exemplary components of a modelsimulation system;

FIG. 8B is a block diagram illustrating exemplary components of acomputer module according to one embodiment; and

FIG. 9 is a flowchart of a process for measuring strain limits of adisplay device in one embodiment.

DESCRIPTION

The following detailed description refers to the accompanying drawings.The same reference numbers in different drawings may identify the sameor similar elements. Also, the following detailed description isexemplary and explanatory only and is not restrictive of the invention,as claimed.

A display device, such as a tablet computer, has a housing or a chassisto hold and protect the components of the device. For example, thechassis may protect the display of the device, including thetouch-screen module that receives input from the user. All too often,users drop their devices, which may cause displays to fail. Asmanufactures design lighter and thinner chassis to improve userexperience, chassis lose stiffness and displays become even more proneto failing when dropped. Although users may be happy with a lighter andthinner device, users are generally not happy when the chassis of theirdevice does not provide adequate protection.

Manufacturers may design and test devices in an iterative process: adevice is designed, made, tested, and designed again based on the testresults. The process repeats itself. For example, a manufacturer maydesign and make a test device with a test chassis. To test the device,the manufacturer drops the device to see whether the display fails(e.g., the touch module fails or the display cracks). If the displayfails, the manufacturer may redesign the device with a redesigned(hopefully improved) chassis, and make the device again but with theimproved chassis. After another drop test, the manufacturer determineswhether the device meets its drop-test requirements.

The design/build/test process described above, however, can be very timeconsuming and expensive. Embodiments described below may enable a morerapid prototyping and testing of devices. As a result, these embodimentsmay enable lighter and less expensive display devices, while stillproviding the desired structural support and protection. As anadditional result, these embodiments may enable manufactured devices tobe more reliable when used by consumers in the field. Because the deviceitself may be lighter, some embodiments enable a more rapid assembly ordisassembly of devices with lighter and faster assembly equipment.

FIG. 1A is a perspective view of an exemplary display device 100, in oneembodiment, manifest as a tablet computer. Although display device 100is shown as a tablet computer in FIG. 1A, display device 100 may be amobile phone, a laptop, or any other device with a display for viewing.Display device 100 includes a display 102 surrounded by a housing 110 toencompass and protect the components of display device 100, includingdisplay 102. The top-most (e.g. exposed) layer of display 102 mayinclude a protective layer 106. FIG. 1A also defines an x-axis, y-axis,and z-axis such that the exposed layer of display 102 is the “top most”layer and the “bottom” of display device 100 is not visible in FIG. 1A.Housing 110 may also be referred to as a “chassis” and it provides theframe to which components of display device 100 are attached,

Even though housing 110 protects display 102, if housing 110 experiencessufficient forces, display 102 may deform and fail. For example, ifdisplay device 100 falls and lands on the floor, glass within display102 could crack. Such a failure may result from strain (e.g., a force)deforming or warping a component of display 102. As an example, FIG. 1Billustrates components of display 102 that may deform or warp to cause afailure.

FIGS. 1B and 1C illustrate display 102 experiencing a force that causesa failure. Display 102 includes color-filter glass layer 112, TFT glasslayer 114, display driver 118, a flexible printed circuit (FPC) 120, anFPC 122, and light-emitting diodes (LEDs) 123. FIG. 1B shows a side viewof these components, whereas FIG. 1C shows a top view of thesecomponents, thus hiding FPC 122 and LEDs 123. Display 102 may includeother components not shown in FIGS, 1B or 1C.

FPC 120 is bonded (e.g., using anisotropic conductive film (ACF)bonding) to TFT glass layer 114 at location 112. FPC 120 carries signalsto display driver 118 from TFT controller 128 to drive pixels on display102. FPC 122 carries signals to LEDs 123 to provide back lighting fordisplay 102. In this example, LEDs 123 are mounted on FPC 122 and FPC122 may be coupled (e.g., affixed) to TFT glass layer 114 with anadhesive. FPC 122 may be connected to an LED controller (not shown inFIGS. 1B or 1C) to control LEDs 123.

In this example, TFT glass layer 114 includes an overhanging portion124. When overhanging portion 124 experiences a sufficiently largeforce, such as drop force 126, overhanging portion 124 may flex (e,g.,deform) in the Z direction (upwardly) and/or in the negative Z direction(downwardly). Drop force 126 may be transmitted through housing 110 andother components of display device 100, for example, when device 100falls onto a floor.

As a result of drop force 126 in this example, TFT glass layer 114fails, as indicated by a crack 130 (shown in FIG. 1C). Crack 130 in thisexample is caused by overhanging portion 124 flexing in the Z direction(and/or in the negative Z direction) because of drop force 126.Designers of display device 100 may wish to design housing 110 so that atypical drop force does not cause crack 130 in TFT glass layer 114, forexample. One cause of display failure (such as a touch-screen displaymodule) in small-form factor devices is dropping the device from aheight of 1.25 m to 1.5 m, or approximately waist to shoulder height.

FIGS. 2A and 2B illustrate exemplary cross-sectional views of displaydevices in different embodiments, such as display device 100 shown inFIG. 1A. For clarity, only a portion of the sectional views are shown inFIGS. 2A and 2B.

FIG. 2A shows a cross-sectional view of a display device 100A in oneembodiment. As shown, display device 100A includes housing 110 and achassis 205A for securing the other components in display device 100A.Other components in display device 100A may include protective layer106A, a touch panel 202A, a polarizer 208A, a color-filter glass layer210A, TFT glass layer 214A, polarizer 216A, light guide 218A, LED 222A,and reflector 226A. The components of FIG. 2A may be referred togenerally without the “A” appended to the reference number. For ease ofunderstanding, display device 100A may include other components that arenot shown, such as optically-clear adhesive (OCA) layers.

Display 102A operates as follows. LED 222A generates light that travelsthrough light guide 218A as aided by reflector 226A. Light from lightguide 218A passes through polarizer 216A and emerges into TFT glasslayer 214A with a single polarization. TFT glass layer 214A includesliquid crystals to change polarization of the light as it passes throughthe liquid crystals to color-filter glass layer 210A. The light emergingfrom color-filter glass layer 210A may be of a particular color (e.g.,red, green, blue). Depending on the polarization of the light (ascontrolled by liquid crystals of TFT glass layer 214A), the coloredlight may or may not pass through polarizer 208A. Colored light thatdoes pass through polarizer 208A then passes through touch panel 202Aand protective layer 106A to the user's eyes. The user may interact withdisplay device 100A by touching touch panel 202A, for example.

TFT glass layer 214A and color-filter glass layer 210A each has a topsurface (facing the positive Z direction) and a bottom surface. As shownin FIG. 2A, the bottom surface of color-filter glass layer 210A isproximate the top surface of TFT glass layer 214A. As used herein, theterms “top” and “bottom” are relative and can be interchanged. TFT glasslayer 214A may extend beyond the color-Filter glass layer 210A to forman overhanging portion 124A, e.g., resulting from a gap 230A above TFTglass layer 214A and a gap 232A below TFT glass layer 214A.

Gap 230A may include FPC 120 and display driver 118 (shown in FIGS. 1Band 1C). Nonetheless, gap 230A may allow for overhanging portion 124A toflex upward (in the Z direction). Gap 232A may include FPC 122 and LEDs123 (shown in FIGS. 1B and 1C). Nonetheless, gap 232A may allow foroverhanging portion 124A to flex in the downward direction (in thenegative Z direction). Such flexing or deformation may result in afailure, such as cracks 130, in TFT glass layer 214A and elsewhere. Asdescribed above with respect to FIG. 1B, flexing of overhanging portion124 may occur when display device 100 drops and a force (e.g., dropforce 126) is transmitted through housing 110 (e.g., or chassis 205A).Flexing of overhanging portion 124A may cause a failure of display 102Ain the form of a crack, for example.

Gap 230A may be between 0.15 mm and 0.25 mm thick, for example. Gap 230Amay have different thickness, such as from 0 to 0.05 mm, from 0.05 to0.1 mm, from 0.1 mm to 0.15 mm, from 0.15 to 0.2 mm, from 0.2 to 0.25mm, from 0.25 to 0.30 mm, from 0.30 to 0.35 mm, or from 0.35 to 0.40 mm.The thickness of gap 230A may depend on the thickness of color-filterglass layer 210A and/or the thickness of polarizer 208A, for example.

Gap 232A may be between 0.2 to 0.3 mm thick. Gap 232 may have differentthickness, such as from 0 to 0.05 mm, from 0.05 to 0.1 mm, from 0.1 mmto 0.15 mm, from 0.15 to 0.2 mm, from 0.2 to 0.25 mm, from 0.25 to 0.30mm, from 0.30 to 0.35 mm, or from 0.35 to 0.40 mm. Depending on themanufacture of display 102A, the thickness of gap 232A may depend on thethickness of light guide 218A and/or polarizer 216A, for example.

Chassis 205A may facilitate assembly of the display device 100A.Further, chassis 205A may facilitate disassembly, reworking, and/orremoval of display 102A from the display device 100A. In other words,protective layer 106A, touch panel 202A, and/or polarizer 208A can beremoved from display device 100A, followed by chassis 205A. Componentscan be repaired or a new chassis 205A (with associated components) canbe installed.

Chassis 205A and/or housing 110 may be formed of any material that canprovide structural support to the display components and/or allowfeatures to be formed therein. Example materials can include variousplastics, polymers, and/or composites, among others. If chassis 205Aand/or housing 110 is formed of metal, for example, display device 100may be heavy and/or thick, but the added weight and/or strength mayreduce the likelihood of display 102A failing during assembly, use, ordisassembly. Although a thicker and heavier chassis 205A and/or housing110 may reduce the likelihood of display 102A failing, a thicker andheavier display device 100A may increase the cost and diminish the userexperience. In some instances, it may be desirable to minimize the cost,weight, and thickness of chassis 205B, and/or housing 110 whileproviding sufficient weight, thickness, and stiffness to protect display102A from failure at reasonable cost. Methods and systems describedherein may, in one embodiment, aid the designer of display device 100Ato achieve this balance between weight, thickness, stiffness,probability of failure, and cost.

FIG. 2B shows a cross-sectional view of a display device 100B. Thecomponents of display device 100B of FIG. 2B operate similarly as thecomponents described for display device 100A of FIG. 2A. For ease ofunderstanding, display device 100B may include other components that arenot shown, such as optically-clear adhesive (OCA) layers.

Chassis 205B performs the function of housing 110 and chassis 205A ofdisplay device 100A as shown in FIG. 2A. As shown in FIG. 2B, TFT glasslayer 214B includes overhanging portion 124B resulting from a gap 230Babove TFT glass layer 214B and a gap 232B below TFT glass layer 214B.Gap 230B extends from TFT glass layer 214B to chassis 205B. Gap 232Bextends from TFT glass layer 214B to reflector 226B. The components ofFIG. 2B may be referred to generally without the “B” appended to thereference number.

Gap 230B may include FPC 120 and display driver 118 (shown in FIGS. 1Band 1C). Nonetheless, gap 230B may allow for overhanging portion 124B toflex upward (in the Z direction). Gap 232A may include FPC 122 and LEDs123 (shown in FIGS. 1B and 1C). Nonetheless, gap 232B may allow foroverhanging portion 124B to flex in the downward direction (in thenegative Z direction). Such flexing or deformation may result in afailure, such as cracks in TFT glass layer 214 and elsewhere. Asdescribed above with respect to FIG. 1B and 1C, flexing of overhangingportion 124 may occur when display device 100 falls and a force istransmitted through chassis 205B to TFT glass layer 214B. Flexing ofoverhanging portion 124B may cause a failure of display 102B in the formof a crack, for example,

Gap 230B may have the same thickness and/or range of thicknesses asdescribed above for gap 230A. The thickness of gap 230B may depend onthe thickness of color-filter glass layer 210B, which may beapproximately the same thickness as gap 230B, for example. Gap 232B mayhave the same thickness and/or range of thicknesses as described abovefor gap 232A. The thickness of gap 232B may depend on the thickness oflight guide 218B and/or polarizer 216B, which may be approximately thesame thickness as gap 232B, for example.

Although a thicker and heavier chassis 205B may reduce the likelihood ofdisplay 102B failing (and potentially causing cracks), a thicker andheavier chassis 205B may increase the cost and diminish the userexperience. In some instances, it may be desirable to minimize the cost,weight, and thickness of chassis 205B while providing sufficient weight,thickness, and stiffness to protect display 102B from failure atreasonable cost. Methods and systems described herein may aid thedesigner of display device 100B to achieve this balance between weight,thickness, stiffness, probability of failure, and cost.

Adding space between layers of display 102A may help to prevent a dropforce (such as drop force 126) from transmitting through housing 110and/or chassis 205 to TFT glass layer 214. For example, protective layer106A and touch panel 202A may be separated by a space from polarizer208A and color-filter glass layer 210A. While this solution may beincorporated with other embodiments discussed herein, adding space wouldincrease the thickness of display device 100A, which may reduce theuser's experience.

Display device 100 (e.g., device 100A or 100B) may include different,fewer, or more components than shown in FIGS. 2A and 23. For example,optically-clear adhesives (OCAs) may bond layers together, such aspolarizer 208 and touch panel 202. Components of display 102 may includemembers to allow components to snap-fit into display device 100.Further, display device 100 may include components, such as a processor,that are discussed with respect to FIG. 6.

FIGS. 3A and 3B illustrate strain gauge 309 and a strain-gaugecontroller 310, in one embodiment, relative to color-filter glass layer210 and TFT glass layer 214. In particular, FIG. 3A illustrates a sideview of color-filter glass layer 210 stacked against TFT glass layer 214in display 102, FIG. 3B shows a frontal view of strain gauge 309 on TFTglass layer 214. An FPC 320 may be bonded (e.g., using ACF bonding) toTFT glass layer 214 at location 304 (shown in FIG. 3B). FPC 320 carriesthe electrical signals from TFT controller 308 to display driver 318,for example, for controlling the polarization of light passing throughTFT glass layer 214.

In one embodiment, FPC 320 may integrate strain gauge 309. FPC 320 mayalso carry electrical signals to and/or from strain gauge 309 andstrain-gauge controller 310. Portions of FPC 320 (e.g., strain gauge309) may be coupled (e.g., affixed) to overhanging portion 124 of TFTglass layer 214 with adhesive, for example. Strain gauge 309 may besplit into multiple sections, such as a section to one side of displaydriver 318, a section to the other side of display driver 318, and asection above display driver 318 (as shown in FIG. 33). When overhangingportion 124 of TFT glass layer 214 becomes deformed, signals indicativeof the deformation and/or strain may be transmitted from strain gauge309 to strain-gauge controller 310 in display device 100.

Strain gauge 309 measures the deformation and/or forces imparted onoverhanging portion 124 of TFT glass layer 214. Strain gauge 309 maymeasure the strain and/or deformation in numerous places on overhangingportion 124. For example, strain gauge 309 may measure strain on one orboth sides of display driver 318. These measurements may indicate notonly the deformation of (and forces on) overhanging portion 124, butalso the other layers of display 102, such as TFT glass layer 214,polarizer 208, touch panel 202, and/or protective layer 106.

FIGS. 3C and 3D illustrate a strain gauge 309′ and LED controller 340,in another embodiment, relative to color-filter glass layer 210 and TFTglass layer 214.n contrast to FIGS.3A and 3B, FIGS. 3C and 3D show aview of strain gauge 309′ on the bottom surface of overhanging portion124 of TFT glass layer 214 (e.g., rather than on the top surface ofoverhanging portion 124). An FPC 322 may be connected to LEDs 123 tocarry signals between LEDs 123 and LED controller 340 for LEDs 123 toprovide back lighting to display 102. Portions of FPC 320 (e.g., straingauge 309′) may be coupled (e.g., affixed) to overhanging portion 124 ofTFT glass layer 214 with adhesive, for example. Strain gauge 309′ andstrain gauge 309 may be referred to generally as “strain gauge 309.”

In one embodiment, FPC 322 may also carry electrical signals to and/orfrom strain gauge 309′ and strain-gauge controller 310. Like straingauge 309, strain gauge 309′ measures the deformation and/or forcesimparted on overhanging portion 124 of TFT glass layer 214. Strain gauge309′ may measure the strain and/or deformation in numerous places onoverhanging portion 124. For example, strain gauge 309 may measurestrain around LEDs 123. These strain measurements may be indicative ofnot only the deformation of (and forces on) overhanging portion 124, butalso the other layers of display 102, such as color-filter glass layer210, TFT glass layer 214, polarizer 208, touch panel 202, and/orprotective layer 106.

When overhanging portion 124 of TFT glass layer 214 becomes deformed,signals indicative of the deformation and/or strain may be transmittedfrom strain gauge 309 (e,g,, strain gauge 309 or 309′) to strain-gaugecontroller 310 in display device 100. As overhanging portion 124 deforms(e.g., warps), a force may be exerted on strain gauge 309 andcharacteristics (e.g., resistance and/or reactance) of components instrain gauge 309 may change. For example, the resistance of a resistor,the capacitance of a capacitor, and/or the inductance or an inductor instrain gauge 309 may change. Strain-gauge controller 310 may detect ormeasure the change in characteristics of components in strain gauge 309and determine the magnitude of strain applied to or degree ofdeformation of overhanging portion 124,

Strain gauge 309 (e.g., strain gauge 309 or 309′) may include anymaterial that has characteristics that can be measured that change inresponse to force on or deformation of one or more components of display102, such as overhanging portion 124 of TFT glass layer 214. In oneembodiment, strain gauge 309 may include one or more thin films spacedat a distance that vary in capacitance when force is applied to one ofthe films (e.g., by the deformation of overhanging portion 124). Inanother embodiment, strain gauge 309 may include one or more componentsthat vary in resistance when force is applied to the components (e.g.,by the deformation of overhanging portion 124). Other embodiments ofstrain gauge 309 may include piezoelectric material and/or opticalmaterials that have characteristics that change when force is applied tothe materials (e.g., by deformation of overhanging portion 124).

The locations of strain gauge 309 and 309′ in FIGS. 3A through 3D areexemplary. FPC 320 and/or FPC 322 may include a strain gauge anywhere inFPC 320 and/or 322 to measure strain on overhanging portion 124. Forexample, FIG. 3E shows strain gauge 309 integrated into FPC 320 inanother embodiment. FPC 320 includes strain gauge 309E above (e.g., inthe negative X direction) display driver 318 as well as to each side ofdisplay driver 318.

Although strain gauge 309 is shown in FIGS. 3A through 3E as coupled(e.g., affixed) directly to overhanging portion 124 of TFT glass layer214, strain gauge 309 may be directly coupled (e.g., affixed) to otherlayers and/or sides of layers in display 102. For example, a straingauge may be incorporated into display device 100 as shown and describedin U.S. patent application Ser. No. 15/385,855, filed Dec. 20, 2016, andtitled “Measuring Strain on Display Device,” which is incorporatedherein. As another example, strain gauge 309 may be directly coupled(e.g., affixed) to either side (e.g., top or bottom) of: color-filterglass layer 210, TFT glass layer 214, polarizer 215, light guide 218,reflector 226, protective layer 106, touch panel 202, and/or polarizer208. In addition, more than one strain gauge 309 may be employed indisplay device 100 (e.g., two, three, four, five, six, seven, eight, ornine or more layers).

As noted above, strain gauge 309 may be attached to any surface of anyof the components of display device 100. Since the components of displaydevice 100 are tightly assembled, the strain measurements of onecomponent are also indicative of the force on or the deformation ofother components of display device 100. For example, strain measured onthe top of TFT glass layer 214 may be indicative of strain on protectivelayer 106, touch panel 202, polarizer 208, color-filter glass layer 210,polarizer 216, light guide 218, and/or reflector 226. Likewise, thestrain measured on the bottom of TFT glass layer 214 may be indicativeof strain on protective layer 106, touch panel 202, polarizer 208,color-filter glass layer 210, polarizer 216, light guide 218, and/orreflector 226.

Further, although TFT LCDs are discussed above, strain gauge 309 may beincorporated into any type of display, such as an organic light-emittingdiode display (OLED) surface-conduction electron-emitter display (SED),field-emission display (FED), cathode ray tube display (CRD),light-emitting diode display (LED), electroluminescent display (ELD),electronic paper or e-ink display, a high-performance addressing LCDdisplay, a quantum dot display, and/or an interferormetric modulardisplay. In fact, the methods and systems described herein may apply todetecting failures (e.g., due to strain) on devices other than devicesthat have displays.

FIG. 4A shows a cross-sectional view of the display device of FIG. 2Awith FPC 320 filling gap 230A and FPC 322 filling gap 232A. FIG. 4Bshows a cross-sectional view of the display device of FIG. 2B with FPC320 filling gap 230E and FPC 322 filling gap 232B.

As shown in both FIGS. 4A and 4B, FPC 320 (incorporating strain gauge309) may enable overhanging portion 124 to resist flexing upward (in theZ direction). Likewise, FPC 322 (incorporating strain gauge 309′) mayenable overhanging portion 124 to resist flexing downward (in thenegative Z direction). In this embodiment, resisting the flexing ordeformation of overhanging portion 124 may prevent a failure, such ascracks (e.g., cracks 130) in TFT glass layer 214 and elsewhere. Parts ofFPC 320 and/or FPC 322 may be affixed to TFT glass layer 214 with anadhesion layer (not shown), for example.

FPC 320, which incorporates strain gauge 309, may he between 0.15 mm and0.25 mm thick, for example. FPC 320 may have different thickness indifferent embodiments, such as from 0 to 0.05 mm, from 0.05 to 0.1 mm,from 0.1 mm to 0.15 mm, from 0.15 to 0.2 mm, from 0.2 to 0.25 mm, from0.25 to 0.30 mm, from 0.30 to 0.35 mm, or from 0.35 to 0.40 mm. Thethickness of FPC 320 may depend on the thickness of color-filter glasslayer 210A and/or the thickness of polarizer 208A, for example.

FPC 322, which incorporates strain gauge 309′, may be between 0.2 to 0.3mm thick. FPC 322 may have different thickness in different embodiments,such as from 0 to 0.05 mm, from 0.05 to 0.1 mm, from 0.1 mm to 0.15 mm,from 0.15 to 0.2 mm, from 0.2 to 0.25 mm, from 0.25 to 0.30 mm, from0.30 to 0.35 mm, or from 0.35 to 0.40 mm. Depending on the manufactureof display 102A, the thickness of FPC 322 may depend on the thickness oflight guide 218A and/or polarizer 216A, for example.

With gap 230 and/or gap 232 filled (e.g., fully or partially) as shownin FIGS. 4A and 43, the likelihood of display 102 failing duringassembly, use, or disassembly may he reduced. Further, with gap 230and/or gap 232 filled, it may be possible to minimize the cost, weight,and thickness of chassis 205 and/or housing 110 while providingsufficient weight, thickness, or stiffness to protect display 102 fromfailure at reasonable cost. Additionally or alternatively, in someembodiments, gaps 230 and/or 232 may be filled with materials other thanFPC and/or a strain gauge (e.g., to resist overhanging portion 124 fromflexing or deforming). For example, some or all of gaps 230 and/or 232may be filled with foam, plastic, polymer, and/or composite materialamong others types of material. Methods and systems described hereinmay, in one embodiment, aid the designer of display device 100 toachieve this balance between weight, thickness, probability of failure,and cost.

FIG. 5 illustrates an exemplary strain gauge 309 and/or 309′ (generallystrain gauge 309) in one embodiment. Strain gauge 309 may be disposedwithin FPC 320 and/or FPC 322 and attached to overhanging portion 124 ofTFT glass layer 214. Strain gauge 309 may include rows of conductors 502and columns of conductors 504 that overlap in separate planes, forexample, forming a mesh 514. In the embodiment of FIG. 5, conductors502, 504 are connected to strain-gauge controller 310 to measure theelectrical characteristics of mesh 514.

In one embodiment, the conductors 502, 504 may include Indium Tin Oxide(ITO). In other embodiments, conductors 502, 504 may include gold,copper, silver, carbon nanotubes, metal oxide, or other conductive orsemiconductive materials. In yet another embodiment, the conductors mayinclude more than one or any combination of these conductive orsemiconductive materials.

As conductors 502, 504 deform (e.g., stretch) and/or move relative toeach other, strain-gauge controller 310 may measure the changingelectrical characteristics of mesh 514. The electrical characteristicsthat change may include the resistance of conductor 502, 504 that isdeformed or stretched, and/or the parasitic reactance and/or resistancebetween any two conductors 502, 504 as the distance between conductors502, 504 changes. The measurement of the resistance and/or reactance indifferent locations of mesh 514 may indicate the strain applied to thedifferent locations, and thus the deformation of TFT glass layer 214and/or color-filter glass layer 210, for example.

The number of locations that strain gauge 309 may measure may behundreds, thousand, tens of thousands, millions, tens of millions oflocations, or more. The number of locations may depend on the number ofhorizontal conductors 502 and/or the number of vertical conductors 504.For example, the number of locations for measurement in mesh 514 asshown in FIG. 5 may be 36 (i.e., the product of the number of horizontalconductors 502 and the number vertical conductors 504).

Strain-gauge controller 310 may continuously or periodically measure theresistance and/or reactance at different locations of mesh 514. Strainmeasurements may be taken by strain gauge 309 every second or fractionof a second (every nanosecond, microsecond, picosecond, or every 0.1,0.01, 0.001, 0.0001, 0.00001, 0.000001 seconds). In one embodiment,these measurements may be received by strain-gauge controller 310,processed by a processor, and recorded in a memory in display device100. Because strain gauge 309 may include analog circuits to measurestrain, mesh 514 may output continuous, analog signals that are sampledand quantized by strain-gauge controller 310. This configuration mayallow for sampling to be performed at the clock rate of processor 610,for example.

As noted above, display device 100 may include more components thanshown in FIGS. 1A through 4B. FIG. 6 is a block diagram illustratingadditional components 602 of display device 100. As illustrated, displaydevice 100 may include a controller or processor 610, an operatingsystem (OS) 612, one or more application programs 614, a memory 620,input components 630, output components 650, a wireless communicationinterface 660, input/output ports 680, a power supply 682, anaccelerometer 686, and/or a physical connector 690.

Processor 610 may include one or more microprocessors, ASICs, signalprocessors, or other control and processing logic circuitry. Processor610 may perform tasks such as signal coding, data processing,input/output processing, and/or power control.

OS 612 may control the allocation and usage of the components in andprovide support for one or more application programs 614, OS 612 mayinclude MICROSOFT® WINDOWS®, Andriod, Linux, Apple iOS, Apple Mac OS,and/or Unix, for example.

In one embodiment, applications 614 can include strain-gauge application614-3. Strain-gauge application 614-3 can send instructions tostrain-gauge controller 310 and receive information from strain-gaugecontroller 310, such as strain measurements. Strain-gauge application614-3 can store these measurements in memory 620 of display device 100.Strain-gauge application 614-3 may be stored in memory 620 executed byprocessor 610. Strain-gauge application 614-3 can implement all orportions of a process, for example, such as the process described belowwith respect to FIG. 9. In some embodiments, OS 612 can implement someor all of strain-gauge application 614-3

In one embodiment, processor 610, memory 620 (storing strain-gaugeapplication 614-3), and strain gauge 309 (e.g., integrated into display102) are in the same display device (e.g., all in the same housing, suchas housing 110 or integrated chassis 205). This embodiment s in contrastto an embodiment in which strain gauges (which are attached to straingauge 309) include wires leading from the display device being testedfor storing strain measurements off of display device 100.

Application programs 614 can also include mobile computing applications(e.g., image-capture applications, email applications, calendars,contact managers, web browsers, messaging applications), or any othercomputing application,

Memory 620 may include non-removable memory 622 and/or removable memory624. Memory 620 may include random-access memory (RAM), read-only memory(ROM), flash memory, a hard disk, or other memory storage devices.Memory 620 (e.g., removable memory 622) can include flash memory or aSubscriber identity Module (SIM) card, as used in a global system formobile communications (GSM) network, or other memory storagetechnologies.

Memory 620 may be used for storing data and/or code for running OS 612and application programs 614. Example data can include web pages, text,images, sound files, video data, or other data sets to be sent to and/orreceived from one or more network servers or other devices via one ormore wired or wireless networks. Memory 620 can be used to store asubscriber identifier, such as an International Mobile SubscriberIdentity (IMSI), and an equipment identifier, such as an internationalMobile Equipment Identifier (IMEI). Such identifiers can be transmittedto a network server to identify users and equipment.

Input components 630 may include a touch device 632 (e.g., touch panel202), a microphone 634, a camera 636, physical keyboard 638, and/orproximity sensor 642. Output components 650 may include a speaker 652and/or display 102. Some components can serve more than one input/outputfunction. For example, touch device 632 and display 102 can be combinedinto a single input/output device.

Communication interface 660 may include a wireless interface (e.g., awireless mode such as a Wi-Fi interface 662 and/or a Bluetooth interface664. Communication interface 660 may be coupled to an antenna (notshown) and may support two-way communication between the processor 610and external devices. Communication interface 660 can include a cellularmodern for communicating with the mobile communication network 604and/or other radio-based interfaces (e.g., Bluetooth or Wi-Fi). Thecommunication interface 660 may be configured for communication with oneor more cellular networks, such as a GSM network for data and voicecommunication within a single cellular network, between cellularnetworks, or between the mobile device and a public switched telephonenetwork (PSTN). Communication interface 660 may include a wiredinterface, such as a physical Ethernet port.

Device 100 can further include an input/output port(s) 680, a powersupply 682, a satellite navigation system receiver 684, such as a GlobalPositioning System (GPS) receiver, an accelerometer 686, a gyroscope(not shown), and/or a physical connector 690, which can be a USB port,and/or an IEEE 1394 (FireWire) port. Components 602 described here arenot required or all-inclusive, as components can be removed and othercomponents included. For example, components 602 may include a physicalkeyboard (not shown).

Any component 602 in device 100 can communicate with any other component602, although not all connections between components 602 are shown.Device 100 can be any of a variety of computing devices (e.g., cell ormobile phone, smartphone, and/or handheld computer) and can allowwireless two-way communication with wired or wireless communicationnetworks, such as mobile communication network 604.

FIG. 7 is a block diagram of an exemplary environment 700 forimplementing methods and systems described herein. As shown in FIG. 7,environment 700 may include a computer device 710, a network 730, targetenvironment 740, display device 100, a processing cluster 750, and adata server 760.

Network 730 may enable any device in environment 700 to communicate withany other device in environment 700. Network 730 may include one or morewired and/or wireless networks. For example, network 730 may include acellular or mobile network, the Public Land Mobile Network (PLMN), along-term evolution (LTE) network, a code-division multiple-access(CDMA) network, a GSM network, a general packet radio services (GPRS)network, a Wi-Fi network, and/or an Ethernet network. Network 730 mayinclude a local area network (LAN), a wide area network (WAN), ametropolitan area network (MAN), an ad hoc network, an intranet, theinternet, a fiber optic-based network, and/or a satellite network.Network 730 may include any combination of these networks.

Computer device 710 may include one or more computer modules, such as apersonal computer, a workstation, a server device, a blade server, amainframe, a laptop, a tablet computer, or another type of computationor communication device. Computer device 710 may include a modelsimulator 720.

Model simulator 720 may include a software tool that enables creation,modification, design, and/or simulation of models representing dynamicsystems. A dynamic system is a system in which a response at any giventime may be a function of its input stimuli, its current state, and/or acurrent time. The model may represent dimensions and physicalconnections (e.g., to specify rigid mechanical connections, voids withvolume flow) operating in accordance with the laws of physics (e.g.,“physics-based rules”). A model of a dynamic system may include, forexample, a model of display 100, a model of a hard surface, and a modelof forces (e.g., gravity) being exerted on display 100 and/or the hardsurface.

The simulation or execution of a model of a dynamic system may includeelemental dynamic systems (e.g., finite element analysis or FEA), suchas a differential equation system (e.g., to specify continuous-timebehavior), a difference equation system (e.g., to specify discrete-timebehavior), and/or an algebraic equation system (e.g., to specifyconstraints). Attributes of the model may include sample times forexecuting the model elements. A simulation of a model of a dynamicphysical system may include a continuous sample time such as acontinuous-time integration function that may integrate an input valueas time of execution progresses. During execution of the model, thecontinuous-time behavior may be approximated by a numerical inte ascheme that is part of a numerical solver. The numerical solver may takediscrete steps to advance the execution time, and these discrete stepsmay be constant or fixed or variable during an execution.

Model simulator 720 may perform FEA for solving strain and forcecalculations on a model of display device 100 (e.g., on color-lifterglass layer 210) under different conditions, such as being dropped froma distance and a model of display device 100 (and components)experiencing a force at a particular location with a particularmagnitude and direction.

Model simulator 720 may be implemented using, for example, MATRIXx fromNational Instruments; MATLAB by The MathWorks. Inc.; Mathematical fromWolfram Research. Inc.; Mathcad from Mathsoft Engineering & EducationInc.; Maple from Maplesoft; Extend from imagine That Inc.; or Modelicaand/or Dymola from Dassault Systemes.

Processing cluster 750 includes processing resources that modelsimulator 720 may use to model a dynamic system including display device100. Processing cluster 750 may include one or more processing unit(s)755. Processing unit 755 may perform parallel processing (e.g., finiteelement analysis) of a model of display device 100 in a dynamic system.Model simulator 720 may send an operation to processing cluster 750 toperform, and processing cluster 750 can divide the operation into tasksand distribute the tasks among processing units 755. Processing cluster750 receives results of the tasks from processing units 755, generates aresult of the operation, and sends the result of the operation to modelsimulator 720.

In one implementation, a processing unit 755 may include a graphicprocessing unit (GPU). A GPU may include one or more devices thatinclude specialized circuits for performing operations relating toperforming a large number of operations in parallel. Processing unit 755may correspond to a single core of a multi-core processor. Processingunit 755 may include a computer device that is part of a cluster ofcomputer devices, e.g., computingdevices operating as part of acomputing cloud.

Data server 760 may include a computing device that manages and/orstores programs and data associated with collecting and analyzingstrain-gauge data. Data server 760 may include one or more programs,such as a web server (e.g., Apache, or MICROSOFT INTERNET INFORMATIONSERVICES® or IIS®), a database (e.g., MySQL, or MICROSOFT ACCESS®), orother applications.

Data server 760 includes one or more computing devices having memory tostore data from display devices 100, such as measurements from straingauge 309 of device 100. In one embodiment, the user of device 100 musttake an affirmative action before data is collected from device 100 andstored in data server 760. Once the user has taken an affirmative actionto store data in data server 760, the user can take an affirmativeaction to prevent any further collection of data. In addition, the userof any device 100 may take an affirmative action to delete any previoususer data stored to data server 760.

Target environment 740 includes the environment in which display device100 will operate. For example, target environment 740 may include “thefield” 744, such as the home of a consumer using display device 100.Target environment 740 may include test fixture 742 where engineers testdisplay device 100 by dropping display device 100 from a height onto ahard surface. Target environment 740 could include the manufacturingfloor during assembly 746 or disassembly 748 of display device 100.Model simulator 720 models display device 100 in these dynamic systemenvironments.

As discussed above, display device 100 may include a set of sensorsand/or a set of controllers (e.g., strain gauge 309). Model simulator720 may receive data (e.g., strain measurements) from display device 100(e.g., through network 730). Model simulator 720 may then use thereceived data (e,g., the received strain limits) as input of parametersto a model of a dynamic system and/or display device 100. As shown inFIG. 8A, model simulator 720 includes a dynamic model 812 and a model814 of display device 100. Model simulator 720 may also include asimulation tool 802, a compiler 804, a code generator 806, a simulationengine 808, and a report engine 810.

Dynamic model 812 may include a model of display device 100 in a dynamicsystem, such as: display device 100 being dropped in a gravitationalfield onto a hard surface; display device 100 being assembled duringmanufacturing; and/or display device 100 being disassembled forrecycling or refurbishment.

Model 814 of display device 100 may include models of components ofdisplay device 100 and/or display 102 (and the interconnections betweencomponents), such as models of chassis 205, housing 110, protectivelayer 106, touch panel 202, polarizer 208, color-filter glass layer 210,liquid crystals 212, TFT glass layer 214, polarizer 216, light guide218, and/or reflector 226. Model 814 of display device 100 associatesstrain measurements that correspond to failures of display 102, forexample. Model 816 of assembly or disassembly equipment may includemodels of components of the equipment that assembles display device 100and/or disassembles display device 100.

Simulation tool 802 may include an application for building a model,such as dynamic model 812 and/or a model 814 of display device 100. Thedesigner of display device 100 can use simulation tool 802 to build amodel having executable semantics, such as a dynamic system model. Thedesigner may use simulation tool 802 to create, display, modify,diagnose, annotate, delete, and/or print, model entities and/orconnections. Simulation tool 802 may provide a user with an editor orgraphical user interface for constructing or interacting with models.

Compiler 804 may compile a model, such as dynamic system model, into anexecutable format. Code generator 806 may generate code from a compiledmodel produced by compiler 804. The generated code may be executed oncomputer device 710 to produce a modeling result. Simulation engine 808may perform operations for executing a model to simulate a system.

Report engine 810 may produce a report based on information in modelsimulator 720. For example, report engine 810 may produce a reportindicating whether a display device 100 satisfies design specifications(e.g., whether glass has broken or not). Embodiments of report engine810 can produce reports in an electronic format for display on outputdevice 880, for example.

Although FIGS. 7 and 8A show exemplary components of environment 700 andmodel simulator 720, in other implementations, environment 700 and/ormodel simulator 720 may include fewer components, different components,differently arranged components, and/or additional components than thosedepicted in FIG. 7. Additionally, one or more components of environment700 and/or model simulator 720 may perform one or more tasks describedas being performed by one or more other components of environment 700and/or model simulator 720.

Devices in environment 700 may each include one or more computingmodules. FIG. 8B is a block diagram illustrating exemplary components ofan exemplary computer module 800 according to one embodiment. As shownin FIG. 83, computer device 800 may include a bus 860, a processor 865,a memory 870, an input device 875, an output device 880, and acommunication interface 885.

Bus 860 enables communication among the components of computer module800. Processor 865 may include, for example, one or more single-coreand/or or multi-core processors, microprocessors, and/or processinglogic (e.g., application specific integrated circuits (ASICs), fieldprogrammable gate arrays (FPGAs), and/or ARM processors) that interpretand execute instructions.

Memory 870 may include a RAM device or another type of dynamic storagedevice that may store information and instructions for execution byprocessor 265. Memory 870 may include a ROM device or another type ofstatic storage device that may store static information and instructionsfor use by processor 865. Memory 870 may include a magnetic and/oroptical recording memory device, and/or a removable form of memory, suchas a flash memory stick. Memory 870 is a computer-readable medium, suchas a non-transitory memory device.

Input device 875 enables an operator to input information into computermodule 800. Input device 875 may include, for example, a keypad, akeyboard, a button, or an input jack for an input device such as akeypad or a keyboard, or a camera. Output device 880 outputs informationto the operator. Output device 880 may include, for example, display102, a light, or a speaker.

Display 102 may include, for example, a cathode ray tube (CRT), plasmadisplay device, light emitting diode (LED) display device, or liquidcrystal display (LCD) device. Display 102 may be configured to receiveuser inputs (e.g., via a touch panel 202).

Communication interface 885 may include a transmitter and/or a receiver(e.g., a transceiver) that enables computer module 800 to communicatewith other devices. Communication interface 885 may include a networkinterface card, and/or a wireless interface card, for example.

Software instructions may be read into memory 870 from anothercomputer-readable medium, or from another device via communicationinterface 885. The software instructions contained in memory 870 maycause processor 865 to perform processes that is described later.Alternatively, hardwired circuitry may be used in place of or incombination with software instructions to implement processes describedherein. Thus, implementations described herein are not limited to anyspecific combination of hardware circuitry and software.

Computer module 800, employed in computing device 710, may performoperations relating to simulating a model of strain and forceexperienced by a model dynamic system including a model of displaydevice 100 (e.g., including a model of a chassis and/or glass). Computermodule 800 may perform these operations in response to processor 865executing software instructions stored in a computer-readable medium,such as memory 870.

Although FIG. 813 shows exemplary components of computer module 800, inother implementations, computer module 800 may include fewer components,different components, additional components, or differently arrangedcomponents than depicted in FIG. 8B.

FIG. 9 is a flowchart of a process 900 for measuring strain limits of adisplay device. Process 900 may be performed by the devices inenvironment 700, such as display device 100 running OS 612 and/orapplication 614-3, and by computer device 710 and model simulator 720.Process 900 is described below with three examples of target environment740. The first example includes dropping display 102 of display device100 in test fixture 742. The second example includes display devicebeing deployed in the field 744 (e.g., with an end user). The thirdexample includes display device 100 being assembled and disassembled inassembly target environment 748 and disassembly target environment 748.

Process 900 may begin by placing a display device 100 (e.g., a test orFirst device) in the target environment (block 902). In the followingfirst example, display device 100 is placed in a test fixture 742 oftarget environment 740. Device 100 includes one or more chassis to holddisplay 102. For example, chassis 205, housing 110, display chassis262A, and/or system chassis 264A hold display 102. A force is exerted ondisplay device 100 and/or the components of display device 100 (block904). In the current example, test fixture 742 may exert force ondisplay device 100 for the purpose of testing the strength of displaydevice 100 and/or display 102. In one case, test fixture drops displaydevice 100 by 1, 2, 3, 4, 5, or more feet onto a hard surface. In oneembodiment, test fixture drops display device 100 from a height ofbetween 1.25 m to 1.5 m. As another example, test fixture 742 has aframe in which display device 100 is mounted and test fixture 742 twistsor bends display device 100.

Process 900 continues by measuring strain on display 102 of displaydevice 100 over a period of time (e.g., a test or first period) (block906) (such as a period of time in which a failure occurs). In oneembodiment, the strain measurements are taken by integrated strain gauge309 in or on display 102 (e.g., on TFT glass layer 214). Strain-gaugeapplication 614-3 (or OS 612) may instruct strain-gauge controller 310to measure strain from strain gauge 309. The measurements may be frommany different locations of strain gauge 309 (e.g., many differentlocations on the surface of TFT glass layer 214). Because strain gauge309 is on the surface of TFT glass layer 214, the strain measurementsmay indicate the degree of deformation of or strain on TFT glass layer214. Since TFT glass layer 214, however, is tightly assembled in display102 with other components, the strain measurements are also indicativeof the force on or the deformation of the other components of display102, such as protective layer 106, touch panel 202, polarizer 208,liquid crystals 212, color-filter glass layer 210, polarizer 216, lightguide 218, and/or reflector 226. Strain may be measured during the testperiod, such as during a fall from a height until after impact on a hardsurface.

As noted above, strain measurements may be taken by strain gauge 309every second or fraction of a second and at hundreds, thousands,millions, or tens of millions of locations. In addition, FPC 320(incorporating strain gauge 309) may enable overhanging portion 124 ofTFT glass layer 214 of display 102 to resist flexing upward (in the Zdirection). Likewise, FPC 322 (incorporating strain gauge 309′) mayenable overhanging portion 124 to resist flexing downward (in thenegative Z direction). Thus, in this embodiment, FPC 320/322 may measurestrain and also resist the flexing or deformation of overhanging portion124 to help prevent a failure, such as a crack (e.g., crack 130) in TFTglass layer 214 and elsewhere.

The strain measurements are recorded (block 908). In one configuration,strain-gauge application 614-3 stores the strain measurements in memory620 of the device being tested (e.g., display device 100 itself). Inanother configuration, strain-gauge application 614-3 stores themeasurements in data server 760. In one embodiment, strain measurementsmay be associated with the time at which the corresponding strainmeasurement was recorded.

In these examples, the user of device 100 must take an affirmativeaction before data is collected and stored in display device 100. Oncethe user has taken an affirmative action to collect and store this datain data display device 100, the user can also take an affirmative actionto prevent any further collection of data. In addition, the user ordisplay device 100 may take an affirmative action to delete any userdata stored to display device 100.

Process 900 includes detecting a failure (block 910) of display 102during the time period. In the current example, failure is broken glassin display 102 (or other catastrophic failure of display 102) whendisplay device 100 lands on the hard surface after having been droppedfrom a height. Detecting a failure may include a visual inspection ofdisplay 102 (e.g., overhanging portion 124) to determine if it has beencracked or otherwise damaged and/or determining if the touch screeninput still functions properly. Detecting the failure may includedetecting one or more broken protective layer 106, touch panel 202,polarizer 208, color-filter glass layer 210, liquid crystals 212, TFTglass layer 214, polarizer 216, light guide 218, and/or reflector 226.

Process 900 includes associating the failure with the recorded displaymeasurements (block 912). In the current example, not all the straingauge measurements are necessarily associated with display 102 breaking.In this case, the maximum strain measurements may be assumed to beassociated with display 102 breaking. In one implementation, application614-3 also stores measurements from accelerometer 686. In this case, thestrain measurements associated with a rapid deceleration or a rapidacceleration may be associated with the failure (e.g., the absolutemagnitude of acceleration passing a threshold). The measurementsassociated with the failure may be referred to as “strain limits.” Thesestrain limits may form part of a model of display 102 used forsimulation of a dynamic environment.

Given the information learned by recording the strain experienced bydisplay device 100, the designer may redesign device 100 (block 914) toreduce the risk of failure. For example, the designer could change orrevise the design of housing 110, system chassis 264, display chassis262, chassis 205, and/or other components of display device 100 to makethese components more or less stiff, for example. Rather thanmanufacture the revised device and test the revised display device 100,the designer may simulate a model 814 of the redesigned display device100. The model 814 of the redesigned display device may include a modelof display 102, in which the strain limits may be associated withfailure.

Thus, process 900 may continue by simulating dynamic model 812 includinga model 814 of a redesigned device (e.g., a revised device or a seconddevice) (block 916). The dynamic model 812 may include, for example,dropping display device 100 (having display 102) in a gravitationalfield whereby it lands on a hard surface. In one embodiment, simulationof the model 814 of the revised display device includes simulating themodel 814 of the redesigned device 100 based on what was learned duringthe test in the target environment, e.g., the drop test and associatedstrain measurements associated with the failure (from block 912). Thatis, the model 814 of the redesigned display device 100 may include amodel of display 102 that failed (e.g., the model of display 102 or afailure of the model of display 102 is informed by or associated withthe strain measurements associated with failure). Model 814 of theredesigned device may include a model of any redesigned component ofdisplay device 100 (e.g., discussed above with respect to FIGS. 2Athrough 2D). The simulation may include modelling the dropping of themodel of display device 100 from a distance (e.g., applying force on themodel of display device 100) and determining if the model of display 102fails. In one embodiment model simulator 720 simulates dynamic model 812including model 814 of display device 100.

If the simulations are not successful (block 918: NO), then device 100may be redesigned (block 914) and simulated again (block 916) until aredesign is successful (block 918: YES). A successful design may be adesign of a chassis (e.g., chassis 205) that result in a failure 5% ofthe time when a force on display device reaches a certain maximum (e.g.,reaches a threshold), for example. Because of the iterative process(blocks 914, 916, and 918), the design and redesign process may beaccelerated (e.g., without having to manufacture every redesign ofdevice 100). This iterative process may be made possible by a betterinformed simulation process, e.g., better informed by strain gaugemeasurements of strain gauge 309 and strain-gauge controller 310.

Once a redesign is satisfactory (block 918: YES), then the redesigned(or second) display device 100 may he manufactured (block 920) andprocess 900 may begin again with the deployment of the redesigneddisplay device 100 being deployed for another test or in the field(block 902). Thus, process 900 may continue in an iterative, rapidprototyping process. The redesigned chassis secures the redesignedsecond display device. Like the first display device, the redesigned,second display device includes a second integrated strain gauge in or onthe second display (e.g., integrated into FPC 320/322) for recordingstrain measurements at a plurality of locations on the display. Thesatisfactory redesign may become the final design, and therefore thesecond (or subsequent) manufacture (block 920) of display device 100according to the satisfactory redesign may be the final product sold toconsumers.

In one embodiment, simulating the model (block 916) of the redesigned(second) display device includes simulating deformation of the model ofthe display based on the identified one or more strain measurements.

This iterative process 900 may continue measuring the strain of thesecond display of the redesigned device over another period (e.g.,second period) of time (block 906) and recording second strainmeasurements (block 908) while applying a force (block 904). Process 900may detect a second failure of the second display during the second timeperiod (block 910) and associate one or more of the second strainmeasurements with the second failure (block 912), Process 900 maysimulate a model of yet another (e.g., a third) redesigned device thatincludes a model of the display (e.g., the display that has failedagain) and a model of yet another redesigned chassis (e.g., a thirdchassis) different than the first chassis and second chassis (block 916)including simulating deformation of the model of the display based onthe identified one or more strain measurements.

In the second example, display device 100 is not deployed in testfixture 742 hut instead is deployed in the field 744 (block 902). Thefield 744 may include test devices given to testers and/or developers oreven products sold to consumers. During this type of testing, displaydevice 100 experiences forces (block 904) through regular wear and tear.Regular wear and tear could include, for example, dropping displaydevice 100 on the ground accidently, sitting on display device 100accidently, or throwing display device 100 to a friend.

During this time, strain-gauge controller 310 and strain gauge 309 maymeasure strain on display 102 and record the measurements in memory 620of display device 100. Display device 100 may also record the time,date, location, and accelerometer measurements associated with timeand/or the strain measurements.

In this example, if display device 100 measures (block 906) and records(block 908) a very high strain measurement that may be associated with afailure (block 910), then the strain measurement (and the otherinformation) may be sent to data server 760. Alternatively, or inaddition, if display device 100 measures and records very highdeceleration or acceleration, then strain measurement, accelerationinformation, and/or other information may be sent to data server 760. Inthis case, strain measurements associated with a rapid deceleration oracceleration may be associated with the failure (e.g., the absolutemagnitude of acceleration passing a threshold).

In this example, the user of device 100 must take an affirmative actionbefore data is collected and stored in data server 760. Once the userhas taken an affirmative action to collect and store this data in dataserver 760, the user can also take an affirmative action to prevent anyfurther collection of data. In addition, the user of display device 100may take an affirmative action to delete any user data stored to dataserver 760.

In one embodiment, the user of display device 100 may be prompted andasked if display 102 of her display device 100 has broken (block 910)(e.g., when strain measurements pass a threshold or deceleration passesa threshold). The user of display device 100 may input into displaydevice 100 whether the display has broken or not. If the display hasbroken (block 910) or if there is no response to the question (block910), then display device 100 may send the strain measurement data todata server 760. In another embodiment, the user of display device 100may be asked (via speaker 652) whether display 102 has broken. The usermay respond by voice via microphone 634 with “yes” or “no.” In thiscase, display device 100 may go through redesign (block 914), simulation(block 916) as described above with the strain measurements returnedfrom the field 744.

In the third example, once strain limits (block 908) are determined, thefollowing dynamic model may be determined: dynamic assembly by assemblyequipment, and dynamic disassembly by disassembly equipment. Assemblyequipment and the assembly process may itself be a model that issimulated or executed by (block 916). Further, disassembly equipment andthe disassembly process may also be a model that is simulated orexecuted by (block 916). Assembly equipment may be lightened andassembly may be accelerated (e.g., the motion of robotic equipment)based on strain measurements (block 912) determined during testing andbased on models 814 of chassis. Disassembly equipment may be lightenedand disassembly may be accelerated (e.g., the motion of roboticequipment) based on strain measurements (block 912) determined duringtesting and based on models 814 of chassis. In one embodiment, theassembly or disassembly equipment may be programmed to move faster orslower, or apply more or less forced based on strain measurements (block912) determined during testing and based on models 814 of chassis.

In one embodiment, assembly and disassembly may occur when the displaydevice 100 is turned on (e.g., OS 612 and/or strain-gauge application614-3 is running). In other words, display device 100 may be deployed(block 902) in the assembly target environment 746 and the disassemblytarget environment 748. In this example, when assembly or disassemblyexerts force on display device 100 (block 904), the strain may bemeasured over time (block 906) and recorded (block 908). Failure can bedetected (block 910) and associated with the appropriate strainmeasurements (block 912). The strain measurements may be used to furtherredesign and simulate new display devices 100. In an alternative method,the strain measured by strain-gauge controller 310 may be reported to OS612.

No element, act, or instruction used in the description of the presentapplication should be construed as critical or essential to theinvention unless explicitly described as such. As used herein, thearticles “a” and “the” and the term “one of” are intended to include oneor more items. Further, the phrase “based on” means “based, at least inpart, on” unless explicitly stated otherwise.

In the preceding specification, various preferred embodiments aredescribed with reference to the accompanying drawings. It will, however,be evident that various modifications and changes may be made thereto,and additional embodiments may be implemented, without departing fromthe broader scope of the invention as set forth in the claims thatfollow. The specification and drawings are accordingly to he regarded inan illustrative rather than restrictive sense,

1. A display module comprising: a thin-film transistor (TFT) glass layerhaving a top surface and a bottom surface; a color-filter glass layerhaving a top surface and a bottom surface, wherein the bottom surface ofthe color-filter glass layer is proximate the top surface of the TFTglass layer, wherein the TFT glass layer extends beyond the color-filterglass layer to form an overhanging portion of the TFT glass layer,wherein the overhanging portion is flexible; and a flexible printedcircuit (FPC) affixed to the overhanging portion, wherein the FPCincludes an integrated strain gauge for measuring strain at a pluralityof locations on the overhanging portion of the TFT glass layer.
 2. Thedisplay module of claim 1, wherein the FPC resists flexing of heoverhanging portion of the TFT glass layer.
 3. The display module ofclaim 2, wherein the FPC is affixed to the overhanging portion on thetop surface of the TFT glass layer.
 4. The display module of claim 2,wherein the FPC is affixed to the overhanging portion on the bottomsurface of the TFT glass layer.
 5. The display module of claim 2,wherein the FPC is affixed to the overhanging portion on the top surfaceof the TFT glass layer and on the bottom surface of the TFT glass layer.6. A device comprising: a display comprising a thin-film transistor(TFT) glass layer having a top surface and a bottom surface, acolor-filter glass layer having a top surface and a bottom surface,wherein the bottom surface of the color-filter glass layer is proximatethe top surface of the TFT glass layer, wherein the TFT glass layerextends beyond the color-filter glass layer to form an overhangingportion of the TFT glass layer, wherein the overhanging portion isflexible, and a flexible printed circuit (FPC) affixed to theoverhanging portion, wherein the FPC includes an integrated strain gaugeto measure strain at a plurality of locations on the overhanging portionof the TFT glass layer; a chassis to secure the display in the device;and a processor, within the chassis, to instruct the integrated straingauge to measure the strain.
 7. The device of claim 6, wherein the FPCresists flexing by the overhanging portion of the TFT glass layer. 8.The device of claim 7, wherein the FPC is affixed to the overhangingportion on the top surface of the TFT glass layer.
 9. The device ofclaim 7, wherein the FPC is affixed to the overhanging portion on thebottom surface of the TFT glass layer.
 10. The device of claim 7,wherein the FPC is affixed to the overhanging portion on the bottomsurface of the TFT glass layer and on the top surface of the TFT glasslayer.
 11. The device of claim 6, wherein the processor is configured toinstruct the integrated strain gauge to measure the strain over a periodof time.
 12. The device of claim 11, further comprising: a memory tostore strain measurements taken by the integrated strain gauge, whereinthe processor is configured to store the strain measurements in thememory.
 13. A method comprising: measuring, over a period of time,strain of a display of a device at a plurality of locations on thedisplay, wherein the display is deformable and secured to the device bya chassis, wherein the display includes an integrated strain-gauge in aflexible printed circuit (FPC) affixed to a portion of athin-film-transistor (TFT) glass layer of the display; recording thestrain measurements in a memory of the device; and associating one ormore of the strain measurements with a failure of the display.
 14. Themethod of claim 13, wherein the FPC is affixed to an overhanging portionof the TFT glass layer of the display.
 15. The method of claim 14,wherein the FPC resists flexing by the overhanging portion of the TFTglass layer.
 16. The method of claim 14, wherein the failure of thedisplay includes a crack in the overhanging portion of the TFT glasslayer of the display.
 17. The method of claim 16, further comprising:simulating a dynamic model including a model of the device, a model ofthe chassis, and a model of the display, wherein the simulation is basedon the one or more of the strain measurements associated with thefailure of the display.
 18. The method of claim 17, wherein simulating adynamic model includes simulating application of a force on the devicecomparable to dropping the device.
 19. The method of claim 16, furthercomprising: simulating a dynamic model including a model of a seconddevice, wherein the model of the second device includes a model of asecond chassis and a model of the display associated with the failure,wherein the model of the second chassis secures the model of thedisplay, and wherein the simulation is based on the one or more of thestrain measurements associated with the failure of the display.
 20. Themethod of claim 19, wherein simulating a dynamic model includessimulating application of a force on the device comparable to droppingthe device.